The Nationals have been searching for a leadoff hitter and center fielder since ... well, since before they were the Nationals.

This is a franchise that has tried in vain for eight seasons to develop or acquire someone who possessed both the ability to play center field and hit at the top of a big-league lineup.

First there was Endy Chavez. Then there was Brandon Watson. Then Nook Logan. Then Lastings Milledge. Then Nyjer Morgan. The list also included, at various times, Justin Maxwell, Marlon Byrd, Willie Harris, Preston Wilson, Ryan Langerhans, Ryan Church, Elijah Dukes, Roger Bernadina, Rick Ankiel and even a guy named Jorge Padilla who even the most knowledgeable Nationals fan would never remember existed.

All told, 32 different men have played center field for the Nationals since 2005 (tied with the Red Sox and Athletics for most in the majors).

So there was some real purpose behind yesterday's trade with the Twins for Denard Span. This wasn't simply an attempt by Mike Rizzo to shore up a small leak. This was an attempt by Rizzo to plug a hole that had existed for eight years.

Will Span be the guy who at long last produces in that vital role? There are no guarantees in life, but he certainly comes to Washington with a far better track record and body of work than any of those 32 previous center fielders.

This is a career .284 hitter with a .357 on-base percentage, spectacular range in center field -- only Michael Bourn rated better defensively last season -- and the ability to put bat on ball. Span struck out in a meager 10.7 percent of his plate appearances last season, well below the league average of 17.2 percent.

He even hits left-handers (.293) better than right-handers (.280) over his career, a rare skill for players of his ilk.

"I think he's going to bring a dimension to the club that we haven't had before," Rizzo said. "A fast-moving, exciting guy that makes contact and moves the ball around and can fly around the field. It gives us added speed, stolen base potential and a guy that can really run down balls, which will further help our pitching staff."

Was the price to acquire Span steep? Yes, it was. Alex Meyer is no slouch, a 6-foot-9 beast of a right-hander whose fastball approaches triple digits and who should be on a fast track to the big leagues after dominating both low- and high-Class A last season.

But the price to acquire Gio Gonzalez one year ago (four top prospects) was far steeper, and you'd be hard-pressed to find anyone complaining about that trade today.

What makes this particular deal all the more fascinating, though, is the domino effect it will have on so many other aspects of the Nationals, in 2013 and beyond.

Span's arrival will push Bryce Harper to one of the corner outfield positions; the hunch here is that he'll go to left field, with Jayson Werth wanting to remain in right field, though those two could wind up swapping spots somewhere down the road.

It also pushes Werth out of the leadoff spot and perhaps Harper out of the No. 2 spot in Davey Johnson's lineup.

All of that, of course, will depend on the name of the Nationals' first baseman in 2013. Will it be Adam LaRoche or Michael Morse? Only one can return.

The easy (and perhaps likeliest) scenario will have LaRoche signing with another club (perhaps the Red Sox, Orioles or Rangers) and Morse shifting to first base. And that may well happen.

But make no mistake, the Nationals still want to re-sign LaRoche, and would prefer to bring him back on a reasonable deal (two, though probably not three, guaranteed years) and then trade Morse (who will be a free agent next winter and most likely won't be re-signed regardless.

Think about this potential lineup should the Nats and LaRoche somehow find common terms:

Even if LaRoche walks and Morse stays, the Nationals still will boast a potent lineup, top-to-bottom. If LaRoche returns, there won't be a better defensive team in baseball.

Above all else, Rizzo has ensured he'll still have plenty of money left over to spend on his remaining offseason needs. If the Nationals don't re-sign LaRoche and don't tender John Lannan a contract before tonight's deadline, they'll have roughly $90 million committed to next year's payroll. (That figure includes the raises all their arbitration-eligible players are likely to receive.)

The Nationals opened 2012 with a payroll of $92 million, and they're perfectly capable and willing to increase that number in 2013. Whether it's LaRoche, a front-line starting pitcher, a veteran reliever or some combination of all that, the funds are there for Rizzo to continue improving a roster that already won 98 games a year ago (without getting a full season of contribution from either Harper or Stephen Strasburg).

Yes, the Nationals are making a real run at winning the 2013 World Series, without sacrificing their chances of winning it in 2014 or 2015. They've got players at seven of the eight everyday positions, four starting pitchers and five relievers under their control for at least the next three seasons.

As always, there are no guarantees in baseball. The Nationals might not win a World Series in the next three years, let alone even reach the playoffs.

But no franchise in the sport is better assembled to win now and down the road than the Nationals. And yesterday's acquisition of Span only made that statement more true.